Stephanie is 51 years old and Umaima is 9 years old. How many years will it take until Stephanie is only 4 times as old as Umaima?
Solution: We can use the given information to write down an equation about how many years it will take. Let $y$ be the number of years that it will take. In $y$ years, Stephanie will be $51 + y$ years old and Umaima will be $9 + y$ years old. At that time, Stephanie will be 4 times as old as Umaima. Writing this information as an equation, we get: $51 + y = 4 (9 + y)$ Simplifying the right side of this equation, we get: $51 + y = 36 + 4 y$ Solving for $y$ , we get: $3 y = 15$ $y = 5$.